﻿using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net;
using System.Text;
using System.Threading.Tasks;

namespace suirui.ZhuMu.Common
{
    public static class FormUpload
    {
        private static readonly Encoding encoding = Encoding.UTF8;
        public static async Task<string> MultipartFormDataPost(string postUrl, Dictionary<string, object> postParameters)
        {
            string formDataBoundary = String.Format("----------{0:N}", Guid.NewGuid());
            string contentType = "multipart/form-data; boundary=" + formDataBoundary;

            byte[] formData = GetMultipartFormData(postParameters, formDataBoundary);

            return await PostForm(postUrl, contentType, formData);
        }
        private static async Task<string> PostForm(string postUrl, string contentType, byte[] formData)
        {
            HttpWebRequest request = WebRequest.Create(postUrl) as HttpWebRequest;

            if (request == null)
            {
                throw new NullReferenceException("request is not a http request");
            }

            // Set up the request properties.
            request.Method = "POST";
            request.ContentType = contentType;
            request.CookieContainer = new CookieContainer();
            request.ContentLength = formData.Length;

            // You could add authentication here as well if needed:
            // request.PreAuthenticate = true;
            // request.AuthenticationLevel = System.Net.Security.AuthenticationLevel.MutualAuthRequested;
            // request.Headers.Add("Authorization", "Basic " + Convert.ToBase64String(System.Text.Encoding.Default.GetBytes("username" + ":" + "password")));

            // Send the form data to the request.
            using ( Stream requestStream = request.GetRequestStream())
            {
                requestStream.Write(formData, 0, formData.Length);
                requestStream.Close();
            }

            //return request.GetResponse() as HttpWebResponse;
            // Get response   
            using (HttpWebResponse response = request.GetResponse() as HttpWebResponse)
            {
                // Get the response stream   
                StreamReader reader = new StreamReader(response.GetResponseStream(), UTF8Encoding.UTF8);
                return reader.ReadToEnd().ToString();                
            }
        }

        private static byte[] GetMultipartFormData(Dictionary<string, object> postParameters, string boundary)
        {
            Stream formDataStream = new System.IO.MemoryStream();
            bool needsCLRF = false;

            foreach (var param in postParameters)
            {
                // Thanks to feedback from commenters, add a CRLF to allow multiple parameters to be added.
                // Skip it on the first parameter, add it to subsequent parameters.
                if (needsCLRF)
                    formDataStream.Write(encoding.GetBytes("\r\n"), 0, encoding.GetByteCount("\r\n"));

                needsCLRF = true;

                if (param.Value is FileParameter)
                {
                    FileParameter fileToUpload = (FileParameter)param.Value;

                    // Add just the first part of this param, since we will write the file data directly to the Stream
                    string header = string.Format("--{0}\r\nContent-Disposition: form-data; name=\"{1}\"; filename=\"{2}\"\r\nContent-Type: {3}\r\n\r\n",
                        boundary,
                        param.Key,
                        fileToUpload.FileName ?? param.Key,
                        fileToUpload.ContentType ?? "application/octet-stream");

                    formDataStream.Write(encoding.GetBytes(header), 0, encoding.GetByteCount(header));

                    // Write the file data directly to the Stream, rather than serializing it to a string.
                    formDataStream.Write(fileToUpload.File, 0, fileToUpload.File.Length);
                }
                else
                {
                    string postData = string.Format("--{0}\r\nContent-Disposition: form-data; name=\"{1}\"\r\n\r\n{2}",
                        boundary,
                        param.Key,
                        param.Value);
                    formDataStream.Write(encoding.GetBytes(postData), 0, encoding.GetByteCount(postData));
                }
            }

            // Add the end of the request.  Start with a newline
            string footer = "\r\n--" + boundary + "--\r\n";
            formDataStream.Write(encoding.GetBytes(footer), 0, encoding.GetByteCount(footer));

            // Dump the Stream into a byte[]
            formDataStream.Position = 0;
            byte[] formData = new byte[formDataStream.Length];
            formDataStream.Read(formData, 0, formData.Length);
            formDataStream.Close();

            return formData;
        }

        public class FileParameter
        {
            public byte[] File { get; set; }
            public string FileName { get; set; }
            public string ContentType { get; set; }
            public FileParameter(byte[] file) : this(file, null) { }
            public FileParameter(byte[] file, string filename) : this(file, filename, null) { }
            public FileParameter(byte[] file, string filename, string contenttype)
            {
                File = file;
                FileName = filename;
                ContentType = contenttype;
            }
        }


        public static string HttpUploadFile(string url, string file, string paramName, string contentType, System.Collections.Specialized.NameValueCollection nvc)
        {
            string result = string.Empty;
            string boundary = "---------------------------" + DateTime.Now.Ticks.ToString("x");
            byte[] boundarybytes = System.Text.Encoding.ASCII.GetBytes("\r\n--" + boundary + "\r\n");

            HttpWebRequest wr = (HttpWebRequest)WebRequest.Create(url);
            wr.ContentType = "multipart/form-data; boundary=" + boundary;
            wr.Method = "POST";
            wr.KeepAlive = true;
            wr.Credentials = System.Net.CredentialCache.DefaultCredentials;

            Stream rs = wr.GetRequestStream();
            string formdataTemplate = "Content-Disposition: form-data; name=\"{0}\"\r\n\r\n{1}";
            foreach (string key in nvc.Keys)
            {
                rs.Write(boundarybytes, 0, boundarybytes.Length);
                string formitem = string.Format(formdataTemplate, key, nvc[key]);
                byte[] formitembytes = System.Text.Encoding.UTF8.GetBytes(formitem);
                rs.Write(formitembytes, 0, formitembytes.Length);
            }
            rs.Write(boundarybytes, 0, boundarybytes.Length);

            string headerTemplate = "Content-Disposition: form-data; name=\"{0}\"; filename=\"{1}\"\r\nContent-Type: {2}\r\n\r\n";
            string header = string.Format(headerTemplate, paramName, file, contentType);
            byte[] headerbytes = System.Text.Encoding.UTF8.GetBytes(header);
            rs.Write(headerbytes, 0, headerbytes.Length);

            FileStream fileStream = new FileStream(file, FileMode.Open, FileAccess.Read);
            byte[] buffer = new byte[4096];
            int bytesRead = 0;
            while ((bytesRead = fileStream.Read(buffer, 0, buffer.Length)) != 0)
            {
                rs.Write(buffer, 0, bytesRead);
            }

            fileStream.Close();

            byte[] trailer = System.Text.Encoding.ASCII.GetBytes("\r\n--" + boundary + "--\r\n");
            rs.Write(trailer, 0, trailer.Length);
            rs.Close();

            WebResponse wresp = null;
            try
            {
                wresp = wr.GetResponse();
                Stream stream2 = wresp.GetResponseStream();
                StreamReader reader2 = new StreamReader(stream2);

                result = reader2.ReadToEnd();
            }
            catch (Exception ex)
            {
                if (wresp != null)
                {
                    wresp.Close();
                    wresp = null;
                }
            }
            finally
            {
                wr = null;
            }

            return result;
        }
    }

   
}
